Cation Mobilities, Including Isotope Effects, for Electromigration in Molten Mixtures of Potassium and Rubidium Nitrate

1979 ◽  
Vol 34 (10) ◽  
pp. 1207-1211 ◽  
Author(s):  
Alf Ekhed ◽  
Dr. Arnold Lundén
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Mass Effect ◽  
Potassium Ions ◽  
Rubidium Nitrate ◽  
Mole Percent ◽  
The Difference

Abstract Electromigration of cations has been studied in molten KNO3 -RbNO 3 mixtures as a function of concentration (11 -94 mole % RbNO3 , about 380 °C) and temperature (about 10 mole % RbNO3 , 378 -560 °C). The mobility of K+ is slightly larger than that of Rb+ at all concentrations, the difference being about 3% in KNO3 -rich and 2% in RbNO3 -rich mictures. Neither for potassium nor for rubidium is the isotope effected affected much by the composition of the melt, although there is a tendency that the isotope effect for rubidium is somewhat larger in mixtures than in pure salts. Both isotope effects have the same temperature dependence in the investigated mixture as in the pure salts. The isotope effects for potassium and rubidium have also been determined for ternary NaNO3 -KNO3 -RbNO3 mixtures containing about 5 mole percent of NaNO3 and of RbNO3 . For comparison, a study of the mass effect for potassium ions in NaNO3 -KNO3 is also reported.

scholarly journals The Temperature Dependence of the Isotope Effect for Electromigration of Potassium Ions in Molten Potassium Nitrate

1968 ◽  
Vol 23 (11) ◽  
pp. 1779-1782
Author(s):  
Arnold Lundén ◽  
Alf Ekhed
Keyword(s):  
Thermal Decomposition ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Separation Factor ◽  
Mass Effect ◽  
Potassium Nitrate ◽  
Relative Difference ◽  
Potassium Ions ◽  
Heavy Isotope ◽  
Significant Enrichment

The relative difference (Δb/b) between the electromigration mobilities of 39K and 41K in molten KNO3 has been measured over the range 354° to 586°C. The mass effect, μ= (Δb/b)/(Δm/m), becomes larger when the temperature is increased, following the relation—,u =0.0385+0.000124 (t-337)where t is the temperature in °C. Due to thermal decomposition, the nitrate is partly converted to nitrite, but it is proved by performing experiments with different initial concentrations of nitrite, that the isotope effect for potassium is not influenced noticeably by the concentration of the anions.The experiment is designed to give an enrichment of the heavy isotope 41K in a small anode compartment and in the upper part of the separation tube. However, it was possible to establish that a slight, but significant, enrichment of the light isotope 39K was obtained in the lower part of the separation tube, i. e. just above the opening into the large cathode compartment. A separation factor of 1.003 was estimated for this enrichment effect, which is due to non-ideal conditions of the experiment.

The Temperature Dependence of the Isotope Effect for Electromigration of Rubidium Ions in Molten Rubidium Nitrate

1972 ◽  
Vol 27 (7) ◽  
pp. 1135-1138
Author(s):  
Arnold Lundén ◽  
Allan Floberg ◽  
Ronny Mattsson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Mass Effect ◽  
Relative Difference ◽  
Rubidium Nitrate ◽  
Similar Temperature Dependence ◽  
Similar Temperature

Abstract The relative difference (Δb/b) between the internal electromigration mobilities of 85Rb and 87Rb in molten RbNO3 has been measured over the range 355 to 500 °C. The mass effect μ = (Δb/b)/(Δm/m) has a complicated temperature dependence. Thus, the largest mass effect, -μ=0.061, was obtained at 445 °C, while it is about 0.033 at 350 °C and 0.041 at 500 °C. A similar temperature dependence was found by SAITO et al. for μNa in pure NaNO3, and for both μRb and μNa maxima have been found also in nitrate mixtures (in KNO3-RbNO3 and NaNO3-KNO3)

Untersuchungen zur Reaktion der Alkoholdehydrogenase mit Tritium-markierten Substraten

1966 ◽  
Vol 21 (6) ◽  
pp. 540-546 ◽  
Author(s):  
Dieter Palm
Keyword(s):  
Alcohol Dehydrogenase ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Substrate Binding ◽  
Isotope Effects ◽  
Direct Interaction ◽  
Enzyme Complex ◽  
Temperature Range ◽  
Yeast Alcohol Dehydrogenase ◽  
Rate Controlling Step

Unexpectedly, the isotope effect of ethanol-1-Τ as a substrate of yeast alcohol dehydrogenase, increases with rising temperature from kH/kT = 3.2 at 5 —15°C to 3.8—4.7 at 20 —35 °C. This suggests a change of the rate controlling step as proposed by MÜLLER-HILL and WALLENFELS, who investigated the temperature dependence of the activation energies in this temperature range. A comparison of the affinities of propanol and butanol with the isotope effects of the corresponding tritium labelled compounds (propanol-1-Τ 6.7 at 25 °C, butanol-1-Τ 6.8 at 25 °C) supports the proposal, that during substrate binding, there must be a direct interaction between the enzyme complex and hydrogen which is removed in the reaction. These influences are less pronounced for the ethanol homologues which are bound less tightly to the enzyme. Therefore the H transfering step proper gives a greater contribution to the overall experimental isotope effect.

Correlation of isotope effects in substitution reactions with nucleophilicities. Secondary α-deuterium isotope effect in the iodide-131 exchange of methyl-d3 iodide

1967 ◽  
Vol 45 (18) ◽  
pp. 2023-2031 ◽  
Author(s):  
Stanley Seltzer ◽  
Andreas A. Zavitsas
Keyword(s):  
Nucleophilic Substitution ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Substitution Reactions ◽  
Deuterium Isotope Effect ◽  
Nucleophilic Substitution Reactions ◽  
Leaving Group ◽  
The Difference

The secondary α-deuterium isotope effect in iodide-131 exchange of methyl-d3 iodide is kH/kD = 1.05 ± 0.01 in methanol and 1.10 ± 0.04 in water at 20°. A correlation of secondary α-deuterium and 13C effects, in bimolecular nucleophilic substitution reactions, with the difference of E values between nucleophile and leaving group is presented.

DEUTERIUM KINETIC ISOTOPE EFFECTS: V TEMPERATURE DEPENDENCE OF β-DEUTERIUM EFFECTS IN WATER SOLVOLYSIS OF ISOPROPYL COMPOUNDS

1961 ◽  
Vol 39 (10) ◽  
pp. 1989-1994 ◽  
Author(s):  
K. T. Leffek ◽  
R. E. Robertson ◽  
S. E. Sugamori
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Zero Point ◽  
Kinetic Isotope Effects ◽  
Methyl Groups ◽  
Deuterium Isotope Effect ◽  
Point Energy ◽  
Kinetic Isotope ◽  
Enthalpy Of Activation

The secondary β-deuterium isotope effect (kH/kD) has been measured over a range of temperature for the water solvolysis reactions of isopropyl methanesulphonate, p-toluenesulphonate, and bromide. In these cases the isotope effect is due to a difference in entropies of activation of the isotopic analogues rather than a difference in the enthalpies of activation. It is suggested that the observed isotope effect is due to internal rotational effects of the methyl groups in the isopropyl radical, and the lack of an isotope effect on the enthalpy of activation is accounted for by a cancellation of an effect from this source and one from zero-point energy.

Electromigration in Molten and Solid Binary Sulfate Mixtures: Relative Cation Mobilities and Transport Numbers

1966 ◽  
Vol 21 (10) ◽  
pp. 1592-1600 ◽  
Author(s):  
Vladislav Ljubimov ◽  
Arnold Lundén
Keyword(s):  
Melting Point ◽  
Eutectic Composition ◽  
Isotope Effects ◽  
Mass Effect ◽  
Cation Transport ◽  
Relative Difference ◽  
The Other ◽  
Transport Numbers ◽  
Li Ion ◽  
The Difference

The electrolytic displacement of the two cations relative to each other has been studied in solid (Li, Ag)2SO4 (93 eq. % Li) at 700 °C, solid (Li, K)2SO4 (91% Li) at 575 °C and molten (Li, K)2SO4 (41 — 90% Li). For melts containing more than about 52% Li the Li ions have a higher mobility (at about 740 °C) than the K ions, while the latter have the highest mobility in mixtures where K is the more abundant cation. The relative difference (Δb/b) between the mobilities of the two cations exceeds 15% already at concentrations some 8% off from the equimobility concentration. For the eutectic composition, 80% Li, Δb/b was about 60% independent of the temperature (590 — 835 °C). For mixtures containing 90% Li it was established that Δb/b changes its sign at the melting point. Thus, the mobility of the Li ion was of the order of half the mobility of the other ion in the solid systems, while it was about twice as large in the melt. The cation transport numbers (relative to the anion) were calculated for all experiments ,and for the melts also the difference between the cation mobilities. An estimation is made of the obtainable accuracy of electromigration experiments.The experiments with melts were analysed for isotope effects. The light isotopes were always enriched towards the cathode, independent of whether Li or K had the higher mobility. The magnitude of the isotope effects shows a concentration dependence, i. e. the mass effect (relative difference in mobility divided by relative difference in mass) tends to increase when an ion is dilute, as previously found for other systems. Thus for the melts with 80% Li, the mass effect is higher for K than for Li.

scholarly journals H/D isotope effect and magnetic properties of cyanide-bridged Nd(III)-Fe(III) complex

2011 ◽  
Vol 1 (1) ◽  
pp. 425-428
Author(s):  
T. Akitsu ◽  
Y. Kimoto ◽  
Y. Yamada ◽  
K. Nomura
Keyword(s):  
Magnetic Properties ◽  
Hydrogen Bonds ◽  
Crystal Lattice ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Mössbauer Spectra ◽  
Isotope Effects ◽  
Intermolecular Hydrogen Bonds ◽  
Coordination Environment ◽  
Mossbauer Spectra

AbstractWe have prepared four H/D isotope forms of Nd(DMF)4(H2O)3Fe(CN)6·H2O (DMF = N,N-dimethylformamide) by using D2O or DMF-d1. Temperature dependence of magnetization exhibits H/D isotope effects resulting from intermolecular hydrogen bonds. Temperature dependence of Fe 2p3/2 and 2p1/2 XAS and 57Fe Mössbauer spectra suggested that the influence of coordination environment could be distiguished from the influence of crystal lattice based on preliminary crystallographic results.

Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions. IV. The Temperature Dependence of the Deuterium Effect for the Reaction of N,N-Dimethyl-d6-aniline and Methyl p-toluenesulfonate. Correlation of Isotope Effects on Activation Parameters

1971 ◽  
Vol 49 (3) ◽  
pp. 439-446 ◽  
Author(s):  
K. T. Leffek ◽  
A. F. Matheson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Isotope Effects ◽  
Nucleophilic Substitutions ◽  
Kinetic Isotope ◽  
Similar Correlation ◽  
Straight Lines

The temperature dependence of the isotope effect for the reaction of dimethylaniline and dimethyl-d6-aniline with methyl p-toluenesulfonate in nitrobenzene solvent has been measured, yielding the result, (ΔHD* − ΔHH*) = −134 ± 30 cal mole−1, (ΔSD* − ΔSH*) = −0.15 ± 0.09 cal mol–1 degree−1.This result has been compared with 15 other temperature dependence studies by plotting ΔΔH* per D atom vs. TΔΔS* per D atom. The points fall on two clearly separated straight lines. A similar correlation is found for a plot of ΔΔG* per D atom vs. ΔΔH* per D atom.The significance of the correlation is discussed and a possible rationalization, in terms of mechanism and particularly the role of the solvent is given.

Carbon-13 kinetic isotope effects. III. Temperature dependence of k12/k13 for 1-bromo-1-phenylethane alcoholysis

1968 ◽  
Vol 46 (8) ◽  
pp. 1435-1439 ◽  
Author(s):  
Jan Bron ◽  
J. B. Stothers
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope ◽  
Increasing Temperature

The temperature dependence of k12/k13 for methanolysis and ethanolysis at the α-carbon of 1-bromo-1-phenylethane has been determined over the ranges 25° and 45° respectively. It is found that the kinetic isotope effect increases with increasing temperature for these systems. This result offers support for earlier interpretations on the 13C fractionations measured previously and the data are considered in terms of the original Bigeleisen equation. The results indicate that primary kinetic 13C isotope effects may be useful for distinguishing between bimolecular and unimolecular substitution mechanisms.

Isotope Effects of Electromigration in Molten Lithium-Potassium Sulfate Mixtures

1968 ◽  
Vol 23 (10) ◽  
pp. 1558-1562 ◽  
Author(s):  
Arnold Lundén ◽  
Vladislav Ljubimov
Keyword(s):  
Transport Mechanism ◽  
Isotope Effects ◽  
Mass Effect ◽  
Relative Difference ◽  
Potassium Sulfate ◽  
Mass Effects ◽  
Low Concentrations ◽  
Eutectic Concentration ◽  
Molten Lithium ◽  
The Difference

The difference in mobility of the isotopes of lithium and potassium has been studied in molten sulfate mixtures over the concentration range 41 to 90 equiv. % Li2SO4. For the eutectic composition (80% Li2SO4) the temperature range 625 to 835°C was covered. The mass effect, μ, (relative difference in mobility divided by relative difference in mass) was calculated. The accuracy, which is much lower for potassium than for lithium, was not sufficient to provide information on the temperature dependence of the mass effects, but it was evident that the ratio between the mass effects of the two cations depends upon concentration. Thus, while the mass effect for lithium is — 0.13 ± 0.02 over the whole range, for potassium it is of the order of — 0.16 for the eutectic concentration and — 0.07 for the mixture with 41% Li2So4. The observed increase of the mass effect at low concentrations is in agreement with results for other systems and can be expected from simple models of the transport mechanism. For lithium the mass effect is the same in the molten sulfate mixtures as in pure fcc lithium sulfate.

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